A known example of a device for manufacturing absorbent cores used for sanitary products (absorbent articles), such as disposable diapers and sanitary napkins, is a fiber stacking device that includes a rotating drum having a collecting/stacking recess in the outer peripheral surface thereof, wherein: a shaped-product material, such as pulp, is supplied to the outer peripheral surface of the rotating drum in a dispersed, airborne state while rotating the rotating drum; the shaped-product material is stacked in the collecting/stacking recess by suction from the bottom surface of the collecting/stacking recess; and the fiber stack in the collecting/stacking recess is released from the collecting/stacking recess by suction from a suction means arranged in opposition to the collecting/stacking recess, and is transferred onto the suction means.
As an example of a rotating drum for the aforementioned fiber stacking device, Patent Literature 1 discloses a rotating drum including a porous air-permeable member, such as a wire mesh, that forms the bottom surface of a collecting/stacking recess, and masking members attached onto the air-permeable member so as to be movable in a predetermined direction, whereby an absorbent core having a desired shape and basis weight distribution can be manufactured by moving the masking members.
Patent Literature 2 discloses a rotating chum including an air-permeable porous plate that has a multitude of suction pores and that forms the bottom surface of a collecting stacking recess, and a honeycomb structure rectifier that is for rectifying the flow of air and that is arranged integrally to the porous plate on the inside thereof. According to Patent Literature 2, the use of such a rotating drum stabilizes the profile of the absorbent core and reduces unevenness in weight of the absorbent core.
Patent Literature 3 discloses a rotating drum wherein a plurality of protrusions, each protruding outward in the drum's radial direction and elongated in the drum's circumferential direction, are formed over the entire area of an air-permeable bottom surface of a collecting/stacking recess. The protrusions are arranged continuously or intermittently in the circumferential direction, and arranged so as to be separated from one another by a predetermined distance in the axial direction of the drum. According to Patent Literature 3, by using such a rotating drum, shaped-product materials are stacked in the recessed spaces other than the protrusions, and thus, the final shaped product (absorbent core) has a plurality of intermittently arranged low-rigidity sections formed by the protrusions, and is thus provided with uniform rigidity and excellent flexibility and is capable of efficiently absorbing body fluid with the entire area thereof.
Patent Literature 4 discloses a rotating drum wherein a spacing member having a plurality of openings, and a gas flaw rate regulating layer having a plurality of openings, are layered in this order on the inner side of a web layer that forms the bottom surface of a collecting/stacking recess (i.e., on the side where shaped-product materials are not stacked). According to Patent Literature 4, the bottom surface (i.e., the web layer) of the collecting/stacking recess is not flat, but the bottom surface has recesses in the central section in the drum's width direction, and thus, sections in the shaped product that correspond to the recesses can be made into high basis-weight sections in which the amount of shaped-product materials stacked is greater compared to other sections.